Ultrahigh pressure-temperature apparatus

ABSTRACT

An improvement in ultrahigh pressure-temperature apparatus in which adiabatic, electrically nonconductive, thermostable cylinders are utilized to protect the outer portions of the apparatus from the pressures and temperatures generated within the innermost parts of the apparatus.

D United States Patent 1151 3,647,33 1

Kuratomi 1 Mar. 7, 1972 [54] ULTRAHIGH PRESSURE- 3,096,544 7/1963Lunblad ..18/D1G. 26 TEMPERATURE APPARATUS 3,201,828 8/1965 Fryklund...18/DlG. 26 3,061,877 11/1962 Custers et al. ,..l8/DlG. 26 [721 f; gai g; 3,383,737 5/1968 Greger ...18/DIG. 26 gas 3,407,445 10/1968 Strong...1s/1)1c. 26 [22] Filed: Mar. 10, 1970 3,249,964 5/1966 Shaler...18/DlG. 26 2,941,252 6/1960 Bovenkerk ...18/D1G. 26 [21] 181433,313,004 4/1967 Vahldiek et al ..l8/DlG. 26

[30] Foreign Application Priority Data Primary ExaminerJ. SpencerOverholser Assistant Examiner-Donald M. Gurley M .1 ,1 69 J ..4417548 at0 9 apan I Attorney-K. W. Brownell [52] U.S.Cl. ..425/77, 425/DlG. 26,425/78,

425/406 ABS IRACT [51] Int. Cl. ..B30b 11/00, B30b 11/32 An im provement1n ultrah1gh pressure-temperature apparatus 0t 26, R, R in adiabaticelectrically nonconductive thermostable cylinders are utilized toprotect the outer portions of the ap [56] References Cited paratus fromthe pressures and temperatures generated within UNITED STATES PATENTSthe innermost parts Of the apparatus.

3,350,743 1 1/ 1967 lshizuka ..18/DlG. 26 3 Claims, 3 Drawing FiguresPATENTEDMAR 71972 3,647,331

FIG!

I PIP/0R ART NTOR. TATJUO K TOM/ ULTRAI-IIGH PRESSURE-TEMPERATUREAPPARATUS BACKGROUND OF THE INVENTION This invention relates toultra-higbpressure-temperature apparatus.

Ultra-high-pressure-temperature apparatus capable of producing andmaintaining pressures of the order of 40,000 to 100,000 atmospheres andtemperatures of the order of 1,000 to 2,500 C. is desirable to effect,control and study reactions occurring under these conditions. Thereactions of various materials subjected to such pressures andtemperatures can be employed for research study purposes or to obtainphysical and chemical changes which desirably alter the characteristicsof the materials. For example, new compounds are known to be formed bysubjecting old materials to very high pressures.Ultra-high-pressure-temperature apparatus is also useful for studyingthe changes in phase of various materials which occur at very highpressures, or for studying the compressibility or electrical, optical ormagnetic properties of various materials. An example of a changeoccurring under these conditions which is of considerable practicalutility is the catalytic conversion of nondiamond carbon to the diamondform.

Prior art high-pressure-temperature apparatus of this type comprisesgenerally (1) a pair of opposed punch assemblies, each of the punchassemblies terminating in a tapered electrically conductive piston; (2)means for exerting pressure on the punch assemblies, whereby anelectrically conductive object positioned between the opposed pistonscan be subjected to high pressure; (3) a lateral pressure-resistingannulus, positioned between the opposed pistons and provided with asubstantially central aperture circumferentially surrounding the objectto be subjected to high pressure, the annulus having apressure-resisting inner wall surface; (4) means for passing electricalcurrent through the pistons and the object to be subjected to highpressure, whereby to produce a high temperature within the objectsimultaneously with the high pressure; and (5) thermal and electricalinsulating gaskets positioned in the aperture of the lateralpressure-resisting annulus and circumferentially surrounding the taperedpistons.

A typical prior art apparatus is illustrated in FIG. 1, wherein alateral pressure-resisting annulus 4 having apressure-resisting innerwall surface 5 is shown surrounding object 7. Opposed taperedelectrically conductive pistons 6 and 6 are urged toward object 7 byconventional means (not shown) to produce high pressure in object 7.Thermally and electrically insulating gaskets 8 and 8 are provided toseparate pistons 6 and 6 from annulus 4, but not from object 7.Electricity is then passed through piston 6, object 7 and piston 6, thusheating object 7 by internal resistance heating. Annulus 4 isstrengthened and reinforced with several layers of steel rings.

Apparatus of this type is frequently capable of pressures in excess of80,000 atmospheres and temperatures in excess of 2,000 C., and furtherdetails of its construction and operation are described in the priorart, for example US. Pat. No. 2,941,248. Such apparatus is subject tothe disadvantage, however, that the pressure-resisting annulus 4 andpistons 6 and 6 bear much of the pressure and heat of the reactionwithin object 7, with the result that these parts are subject tofracture and frequently need replacement. Furthermore, it is difficultto enlarge any given annulus 4 to accommodate a larger object 7,inasmuch as the inner walls 5 of cylinder 4 are tapered toward itscenter.

SUMMARY OF THE INVENTION It is, therefor, an object of this invention toprovide a new and improved high-pressure-temperature apparatus of thetype described which overcomes the above-noted problems of the priorart. These and other objects are achieved by providing thepressure-resisting inner wall surface of the pressure-resisting annuluswith a vertical cylindrical shape, and in combination therewith, anadiabatic, electrically nonconductive, thermostable hollow cylinderpositioned within the aperture of the lateral pressure-resisting annulusand circumferentially surrounding the object to be subjected to highpressure (e.g., a reaction chamber for the conversion of nondiamondcarbonaceous material to diamond). The outer portions of the apparatusare thus protected from the pressures and temperatures within theinnermost parts of the apparatus. Further details and preferredembodiments are indicated below.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional schematicdiagram of the central portion of conventional high-pressure-temperatureapparatus as described above.

FIG. 2 is a sectional schematic diagram of the central portion ofapparatus according to the present invention.

FIG. 3 is a sectional view of the apparatus of FIG. 2, taken along line3-3 ofFIG. 2.

DETAILED DESCRIPTION Referring now to FIGS. 2 and 3 of the drawings, theapparatus of the present invention will now be described in detail.

Lateral pressure-resisting annulus l 1 having a vertical cylindricalshape for its pressure-resisting inner wall surface surroundscircumferentially the object 20 to be subjected to high pressure.Materials which can be used for annulus 11 include ultrahard alloys,high-speed steel and die steel; these materials themselves are known inthe art. Above and below object 20 are opposed punch assemblies (notshown), terminating in tapered electrically conductive pistons 12 and12'. It should be noted that references herein to above," below,lateral"and the like are merely indicative of orientation when theapparatus is arranged with the pistons 12 and 12' in a verticalconfiguration, and the apparatus need not be so arranged. Thisdesignation is convenient, however, in indicating the relativeorientation of the various parts of the apparatus herein described.Materials which can be used for pistons 12 and 12' include die steelsand ultrahard alloys such as cemented tungsten carbide. One such alloywhich is commercially available contains 94 percent tungsten carbide and6 percent cobalt.

Within the aperture of lateral pressure-resisting annulus 11 andcircumferentially surrounding object 20 is an adiabatic, electricallynonconductive, thermostable hollow cylinder 15. Preferred materials forcylinder 15 include thorium oxide, zirconium oxide, hafnium oxide andmixtures thereof. In order that temperatures of 2,500 C. can begenerated within object 20, the material for hollow cylinder 15 musthave a melting point of at least 2,600 C. and be adiabatic andelectrically nonconductive. Materials with sufficiently high meltingpoints and electrical resistivities include the following:

Material Melting Point Thorium Oxide 3,300" C. Magnesium Oxide 2,825 C.Zirconium Oxide 2,700" C. Calcium Oxide 2,630 C. Hafnium Oxide 2,800 C.

Of these materials, however, calcium oxide and magnesium oxide are notpreferred because of their comparatively high thermal conductivities.Calcium oxide has the further disadvantage of reacting with carbon attemperatures above 2,000 C. to form calcium carbide. The carbonizationreaction advances rapidly and continuously, whereas the carbides ofthorium and zirconium, for example, form thin filmy protective coatingson the inner face of hollow cylinder 15, so that further carbonizationdoes not occur.

In a preferred embodiment of this invention, there is provided a pair ofadiabatic thermostable discs 19 and 19', disc 19 being positioned aboveobject 20, between object 20 and piston 12; and disc 19' beingpositioned below object 20, between object 20 and piston 12'. Discs 19and 19' are of such diameter, however, as to allow the passage ofelectrical current from one piston to the other piston'through object20.

This is.preferably accomplished by providing (1) a pair of electricallyconductive rings 17 and 17 surrounding discs 19 and 19', respectively,and in electrical contact withpistons l2 and 12', respectively; and (2)a pair of electrically conductive discs 18 and 18', disc 18 beingpositioned above object 20, between object 20 and disc 19; and disc 18being positioned below object 20, between object 20 and disc 19'. Discsl8 and 18 are simultaneously in electrical contact with rings 17 and17', respectively, on the one hand, and object 20 on the other. Thuselectrical current can pass from piston 12 to ring 17 to disc 18 toobject 20 to disc 18 to ring 17 to piston 12, while pistons 12 and 12'are shielded by adiabatic thermostable discs 19 and 19 from the heat andpressure generated in object 20. Preferred materials for adiabaticthermostable discs 19 and 19 include thorium oxide, zirconium oxide,hafnium oxide, and mixtures thereof.

A still more preferred embodiment of this invention includes a secondadiabatic, electrically nonconductive, thermostable, hollow cylinder 14positioned within the aperture of the lateral pressurerresisting annulus1 l, and circumferentially surrounding (l) the first adiabatic,electrically nonconductive, thermostable, hollow cylinder 15; (2) theadiabatic, thermostable discs 19 and 19'; (3) the electricallyconductive rings 17 and 17'; (4) the electrically conductive discs 18and 18'; and (5) the object 20 to be subjected to high pressure,Preferred materials for adiabatic, electrically nonconductive,thermostable, hollow cylinder 14 include zirconium oxide, pyrophyllite,and mixtures thereof.

A still more preferred embodiment of this invention includes a metallichollow cylinder 13, positioned within the aperture of the lateralpressure-resisting annulus 11 and circumferentially surrounding thesecond adiabatic, electrically nonconductive, thermostable, hollowcylinder 14. Cylinder 13 should be of a metallic material of greathardness and tenacity so as to reduce the high pressures-generatedwithin the apparatus (by urging pistons 12 and 12' towards object 20),and thereby subject annulus 11 to less stress than would otherwise bethe case. Thus annulus 11 is able to maintain its hardness and tenacitywithout being melted or worsened in quality by the full heat andpressures generated within object 20. Preferred materials for cylinder13 include ultrahard alloys, high-speed steel, die steel andceramic-metallic (cermet) alloys.

By the use of cylindrical shapes for the pressure-resisting inner wallsurface of pressure-resisting annulus 11 and for cylinders l3, l4 and15, these innermost parts which bear the greatest heat and pressure ofthe apparatus can easily be replaced, if need be. The cylindrical shapealso aids in the transmission of pressures from pistons 12 and 12 toobject 20.

Thermal and electrical insulating gaskets l6 and 16, preferably ofpyrophyllite, surround pistons 12 and 12', respectively, to complete theportion of the apparatus shown.

I claim:

1. In a high-pressure-temperature apparatus for subjecting an object tohigh pressure, comprising: (a) a pair of opposed,

tapered, electrically conductive pistons; (b)a lateral,pressure-resisting annulus, positioned between the opposed pistons andcoaxial therewith, provided with a substantially central aperturecircumferentially surrounding the object to be subjected to highpressure, the annulus having a pressureresisting inner wall surface; and(c) a thermal and electrical insulating gasket positioned in theaperture of the lateral pressure-resisting annulus and circumferentiallysurrounding the tapered pistons, the invention which comprises theprovision of a vertical cylindrical shape for the pressure-resistinginner wall surface of the pressure-resisting annulus, and in combinationtherewith l) a first adiabatic, electrically nonconductive,thermostable, hollow cylinder, positioned within the aperture of thelateral, pressure-resisting annulus, and circumferentially surroundingthe object to be subjected to high pres sure, said first adiabatic,electrically nonconductive, thermostable, hollow cylinder consistingessentially of thorium oxide, zirconium oxide, hafnium oxide, ormixtures thereof; (2) a pair of adiabatic, thermostable discs, one discbeing positioned above and one disc being positioned below the object tobe subjected to high pressure, between said object and the opposedpistons; said discs being of such diameter as to allow the passage ofelectrical current from one piston to the other piston through theobject to be subjected to high pressure, said adiabatic, therrnostablediscs consisting essentially of thorium oxide, zirconium oxide, hafniumoxide, or mixtures thereof; (3) a pair of electrically conductive rings,each ring surrounding one of the adiabatic thermostable discs and beingin electrical contact with one of the opposed pistons; (4) a pair ofelectrically conductive discs, one electrically conductive disc beingpositioned above and one electrically conductive disc being positionedbelow the object to be subjected to high pressure, between said objectand the adiabatic therrnostable discs, each of said electricallyconductive discs being electrically in contact with one of theelectrically conductive rings and with the object to be subjected tohigh pressure; (5) a second adiabatic, electrically nonconductive,thermostable, hollow cylinder, positioned within the aperture of thelateral pressure resisting annulus and circumferentially surrounding (a)the first adiabatic, electrically nonconductive, thermostable, hollowcylinder; (b) the adiabatic, thermostable discs; (c) the electricallyconductive rings; (d) the electrically conductive discs; and (e) theobject to be subjected to high pressure; said second adiabatic,electrically nonconductive, thermostable, hollow cylinder consistingessentially of zirconium oxide, pyrophyllite, or mixtures thereof; and(6) a metallic hollow cylinder, positioned within the aperture of thelateral pressure-resisting annulus and circumferentially surrounding thesecond adiabatic, electrically nonconductive, therrnostable, hollowcylinder.

2. The invention of claim 1 wherein the first adiabatic, electricallynonconductive, thermostable, hollow cylinder consists essentially ofhafnium oxide.

3. The invention of claim 1 wherein the adiabatic, thermostable discsconsist essentially of hafnium oxide.

1. In a high-pressure-temperature apparatus for subjecting an object tohigh pressure, comprising: (a) a pair of opposed, tapered, electricallyconductive pistons; (b) a lateral, pressure-resisting annulus,positioned between the opposed pistons and coaxial therewith, providedwith a substantially central aperture circumferentially surrounding theobject to be subjected to high pressure, the annulus having apressureresisting inner wall surface; and (c) a thermal and electricalinsulating gasket positioned in the aperture of the lateralpressure-resisting annulus and circumferentially surrounding the taperedpistons, the invention which comprises the provision of a verticalcylindrical shape for the pressure-resisting inner wall surface of thepressure-resisting annulus, and in combination therewith (1) a firstadiabatic, electrically nonconductive, thermostable, hollow cylinder,positioned within the aperture of the lateral, pressure-resistingannulus, and circumferentially surrounding the object to be subjected tohigh pressure, said first adiabatic, electrically nonconductive,thermostable, hollow cylinder consisting essentially of thorium oxide,zirconium oxide, hafnium oxide, or mixtures thereof; (2) a pair ofadiabatic, thermostable discs, one disc being positioned above and onedisc being positioned below the object to be subjected to high pressure,between said object and the opposed pistons; said discs being of suchdiameter as to allow the passage of electrical current from one pistonto the other piston through the object to be subjected to high pressure,said adiabatic, thermostable discs consisting essentially of thoriumoxide, zirconium oxide, hafnium oxide, or mixtures thereof; (3) a pairof electrically conductive rings, each ring surrounding one of theadiabatic thermostable discs and being in electrical contact with one ofthe opposed pistons; (4) a pair of electrically conductive discs, oneelectrically conductive disc being positioned above and one electricallyconductive disc being positioned below the object to be subjected tohigh pressure, between said object and the adiabatic thermostable discs,each of said electrically conductive discs being electrically in contactwith one of the electrically conductive rings and with the object to besubjected to high pressure; (5) a second adiabatic, electricallynonconductive, thermostable, hollow cylinder, positioned within theaperture of the lateral pressure resisting annulus and circumferentiallysurrounding (a) the first adiabatic, electrically nonconductive,thermostable, hollow cylinder; (b) the adiabatic, thermostable discs;(c) the electrically conductive rings; (d) the electrically conductivediscs; and (e) the object to be subjected to high pressure; said secondadiabatic, electrically nonconductive, thermostable, hollow cylinderconsisting essentially of zirconium oxide, pyrophyllite, or mixturesthereof; and (6) a metallic hollow cylinder, positioned within theaperture of the lateral pressureresisting annulus and circumferentiallysurrounding the second adiabatic, electrically nonconductive,thermostable, hollow cylinder.
 2. The invention of claim 1 wherein thefirst adiabatic, electrically nonconductive, thermostable, hollowcylinder consists essentially of hafnium oxide.
 3. The invention ofclaim 1 wherein the adiabatic, thermostable discs consist essentially ofhafnium oxide.